There are many commercial, industrial, and retail environments, such as factories, stores, warehouses, and office buildings that are equipped with a large number of lighting fixtures with installed fluorescent tubes, such as tubes of the types designated as T8 or T12, and accompanying electromagnetic (EM) ballasts.
LED-based luminaires tend to be advantageous replacement solutions for fluorescent tubes. LED-based tubes are commonly designated as “LED tubes” or by the acronym “TLEDs”. There are various existing LED tubes nowadays, most of them being designed to be supplied by a mains input, such LED tubes being commonly designated as “mains compatible”.
One of the main challenges in designing LED tubes is to make the products fail-safe on various existing ballasts. Mains compatible LED tubes available nowadays are not fully safe on EM ballasts. Such LED tubes are typically comprising an input rectifier comprising a diode bridge. However if it occurs that any of the diodes of the diode bridge fails, then a direct current will flow through the EM ballast, and the EM ballast will be at risk of overheating if the lamp input fuse does not blow under such a fault condition.